OK I have an updated script. You can place this in your top directory. So I have my Gdrive (for google to read with comiccat wherever I am), then a comics folder under that.
Change the first 3 lines:
set BaseDir=y:\gdrive\
set ComicDir=comics\
set ZipDir=C:\Program Files\7-zip

To you base directory, comic directory (if it's comic, set base to like y:\)
Set ZipDir to your 7Zip directory.

Then once it's run you'll have a BatchErrors.txt that will show if any of the Comic's failed to extract/recompress (Usually this means the CBR/CBZ is bad, so redownload, or sometimes if using usenet there are bad ones).